SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b2a144a467626855f9774cf8ade7c7bdd840f36eb4a935d05e5a0a278852124c' 
  AND token = 'qYdD9rWEKtkooqadyVCx4wmacMVrzCnap/XEIi1iLkk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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