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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b21c3372dbfc7667b845cc8c683a9469f6373645e6221cf0bc2e1454c8afb23f' 
  AND token = 'cl5EHm89OEr1XchXQrIfRtrK/wO1DYmXs6uJ231g/ho=' 
  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"
    }
  }
}