SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9e6d69d72a063fee0a3d0f28fc37cb7a083d4d41b53d5654053702e43183c378' 
  AND token = 'srMCFw3zK+HyqtwTnU/rRpWcZsG251PAmwRAXnAlvy4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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