SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'c78b3cc963510afac69d9b6dbeff2a116e4d94bf05a231a166aa985cc5ec0221' 
  AND token = 'p3VhbLY2BUzTO8X9nrGXAvcwtciEv8W0Lu9yCQLlMkw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00040

JSON explain

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