SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1a1f67ce38a8c104cab1d9ec442ad96bdcf40c85d0a0e323bda563f7ac3b4e91' 
  AND token = 'PTh59/q9mCVonlYh8MCzW1UZt7DEorBmQuvVKZKHmF8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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