SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '047d1757e20f193f169b7575d6e9a30c6ab4af710d591af9a1ade1b9df40e131' 
  AND token = 'ObmFR8cWDnjMQ1dLDiMNcbrt7nnvsXMr5lYwZi5cm/g=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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