SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '703f0561ef04b574f20a67f5b673db2b8b908635addbd456b4ca8398431eb017' 
  AND token = 'NBBPRYiz30qWYWWhWvAEsiHNHG5kzr4tcfDyOJ+LXjI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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