SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'df7f740715542b230c69f211d63699352dac3b302d9c5793bac0a71039e1040f' 
  AND token = 'c6IQa4Dzu9DL4DZqMxySykK2aOWqfQqD0po89/8U7mQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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