SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7f5249cca3159053104a577087e90b41bb0b155fc71d412a41a0766aff566c8f' 
  AND token = 'o9HJMNgo3sESspLJKysmpVxqP4l/bo2dVQBmJVkv9Jc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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