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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a389cffebcdd4ba384229695419ec5b19e30c524fb1c89e883a80d3d2d43ff37' 
  AND token = 'rA0S8EPqpXMIEk/MdeKd7FiEQyGZcUPBzGAxXdX46Oc=' 
  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"
    }
  }
}