SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'dd813a811ddba186e84396bc6a4608419df59ac74247f6ed8548fb8a36a56875' 
  AND token = 'z0/0SABf3nWI5RolYfhP2ROEJwNokWgyg8PzgKY/CKc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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