SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '61f888d1a3d78c7de24b1778c8fd74c29795a5f6984d19e10465e053757a9b5a' 
  AND token = 'ZS4K0N4ZGuTVHg+AsSmpzrQOP5xEpxK/OlROJNr+/vU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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