SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2febc6050dd28fe3835821dc06c84b34fc50ec8b18bfd94734227f8894f62a3c' 
  AND token = '94k2LN9KIh44y2kmGa0kQjrchQfv0OQgNCMQUcilXVE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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