SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = '684e7f564bcec9b67e804a10fc6a00e38536286760b3c2cc004957e6a61b5426' 
  AND token = 'YwADzJgTqhHNV0tOXRPAaEuMIq0D/pN7jQKmSdZCdaU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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