SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ccc473d01d12a889570cdea4adeeaf77e76a30a32402400d496bdb4ccbddc281' 
  AND token = 'YcaPHxQQukCiwYQAsFrq3CAcVjOLEdfj/BH9Vtbzdg0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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