SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '35b86785d9f88b4c5733197e2724c294da2145f621cc6ac561ce966260f8d154' 
  AND token = '91DNGhm4rKQpHhjgVxUg7uPRZTfsUh5Q0VAk3cWv59g=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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