SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6f19bc2435564c01b9c3d58336634adabebdb03e7501dac8e27e02570a1bf843' 
  AND token = 'lEIl9tm4QETBjCQgoKBwg+0CRIv0QqTV/pWjrM/jpRQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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