SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '34ad7351ebcb7c64c62c1aa39f514d6128c538287c483c0ad102a2555cfbf940' 
  AND token = 'JUMiW6GIhS+MJmA9Hs/lfC4fQzX/TnTz9TJOGRaIfAA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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