SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3ec10611232aeaa485d0b3df548c97494618eafa982b5230a3fb8c65382c4750' 
  AND token = 'YHmrfSnidNdhVwHOLp44x/8yXQ79xpBwP42tpK/3na4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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