SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b5351d44accbcec65ea3dce288ba2831e647468c649a4915b9e7d7a47f7f4951' 
  AND token = 'y/V3SgJx8pAxdmF7Eftj2Zy3iPEcgQbnpnTbv5/vz9s=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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