SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f76729e045d754f2afb899951cc86f33d3e4ecf3aa8201350b3a49f869747c4c' 
  AND token = 'yBdu02ZPThmOKzU6eWjvjmlB73qWGTdY/Ks7RUtKO/Y=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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