SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fd712a534a558a0ccacde481046cfe9fcb76a610f0502fc2bb16838e53a46821' 
  AND token = 'u3ytBiDpCyWDOHqzQ6MO3UDJS3yinwpAVYuYGCvuxgs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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