SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '74d31824d1f8674767ec648c97611e19d921183b91517a2735c27b304e788cf3' 
  AND token = '6AzzHcspXesR8OPlpfeBv7DvukQhCVwgN/Lu+9AxjFw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00052

JSON explain

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