SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3a3bc99f41f356ed4368b55cef37412a1f63218fb93dd37dc5194057a456dce7' 
  AND token = '3zBudICbh/1qY/qivTc9Gb6zlsNA5gZKimlQSh0qn0I=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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