SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ec1b9bcfadfe338c6787acfa0cf4b430ae1f7170860ffe3eac93dc11b3ff6074' 
  AND token = 'rQrpkzehmDhZjQ9oE2b6IgHMvm+seWKk8+0RKYXVDFQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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