SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '98b7a4d635375203937f19720627cb7bfdd98b7f4b7352212a98c189feea689a' 
  AND token = 'yrxRRZbCMyhdWqqm2rGuBCRJaTXnMgiWXBPI2qhwB2Y=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00046

JSON explain

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