SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '46cd9c484dc79ec4090d809bd09313fe03daa19bc0cc6bc972bfba9335831445' 
  AND token = 'osOJ7DM/kynE9Uq3hzp80C3XmIBb6K6VjW5x7HxAtJg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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