SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '23518839ca249bf05c8f8af3e296449c22c2518894ca90b02028bbfd373cf37f' 
  AND token = 'vtViwC3UKJZID65uknwOEDoFCDZclY6UhIJ3KZBLuqQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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