SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7f8d43247f0c32a2a65ad0b9a1c6b64cb6a84c6134ea2604ce7944c29be1f0bf' 
  AND token = 'nIbCdlPZq5PjC2Iu6kX+OHjDqQCTXy4UiHfdew+e6HI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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