SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6e39906628b0bfa3dd84ecd91824706706fb20bc6f292b392a29899259dee8a4' 
  AND token = 'yGf5UCXFDmgO5nX1oz/mmzuRRtcLqZFd61Bu3Lh3Fqg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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