SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '278f8b83b236cbb7cbc12b4905b930ed0a6898a2bca24c9986adf1221626d101' 
  AND token = 'vtWWKTDJbW1VOsG4Xzqug+R19mzXJlCGFvOcPL6ORH8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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