SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '45a28bad4f130470a418bad74dd12824f8e064ca7340e2993103404b82b6c69c' 
  AND token = 'ODvSA3g8Q6si1PgZ4rf9UNL38mskM8cj+q2NWH7UAO0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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