SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '556e07aba2325ea16c61be9e7272ff90e9e53a9788b9f993595a0f338df43cc8' 
  AND token = 'BViF+ZT6VZW/SunBdBULHvqi48DMBF3HismzxuCacMk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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