SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7f4f617d4031c7085fa50ea6d908f0bddc9653646589c18f3bbd92aa9e079760' 
  AND token = '/JJOfyYssmZhqiUWaibXBwwK1+szg34gYnWdo0ccUgc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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