SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd735d8347e253d277bb7b815db734229436a75318dcf70808f46f3a9e2a0a1df' 
  AND token = 'Stw5AUqAKyGmouW+hwMbF1Zi7AXCGOJmonFUBbQn8hs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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