SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '83ced18b7ef981469026e176bd3652564b2e1f84b8c6201558d638c80dcc46f8' 
  AND token = 'Sh3O0H6KLWfW1vdfRm3qp1ImVfSj3/VEZspCGSs6k7w=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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