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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '31f5cc03925c535a3a6a7285c070837449aba59ceb21a2a6a5d59c42c7aff5d0' 
  AND token = 'e4AbRNRgcQRwklSQimf99oD2uekWfwgZft96kW96Xfg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}