SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '818a22d944fd70587fa20066e44867f82eb38e54de96fc1e9d8f391927dda1a6' 
  AND token = '48Ow7uyG1hSlVbvvBUkvxefNE6jz2ZfLLcoYpp6KOSg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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