SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '83197edbd974b332851724f71b9ed4513ce096c07e8021451901aa3747d792b4' 
  AND token = '9i7hDQirMlPiA7D3mTCSh6Nfy+kzj+sD8GqXF0Cy0e8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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