SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '0173d38f97cfdf001ea8bb5d95c40678057577e7a91878382437390ca5867d91' 
  AND token = 'RC9XzP1oY2DXGB4MHmvdgvg4ByWKE+c/Yx3/EG1MVr8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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