SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4c763392ac3a770dd4beef9975857089db7265954cf6ae26f439798fad206b29' 
  AND token = 'z1kkXovnRG3UDUqdmYsyHwA+YJTq+ATZ16cxZ6ukXHI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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