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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b4f8de8715955ad43ab5d56fe0cb79513434e4dabc3d7da5077f3f7f1d1f4eec' 
  AND token = '8EqagkrVQqhcCzw5G1o6HnlkMiXm9kQQQvUdBrIDT9s=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00043

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}