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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'd45bfe0af5dfc1a47dca864d31e6421903c53b28107ed2d66af82a94789a6cd3' 
  AND token = '0/0yk4CLqhRwLRpwCPECaflN+zN7S/XKPfiuk59AD5s=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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