SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '476ea34f08207f876611c4054cfe1ed9980b4f03a6cfdc21154a506c526cda3f' 
  AND token = 'H5i/s2y1N6TkublfIQaS9MeM5B1+UtxUafMRPn2eHJQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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