SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '18a87274de64df43a447ca045115313967782b7ade873b67369835f122c14036' 
  AND token = 'OxZesmOpqgP4Z6QBpdpRKFPgsor/ZKF1jdISBGAGsr4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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