SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6b9290764982146569ac052b342b93536bd0d295eac9f40e0db82df5bd965dfc' 
  AND token = '3CFrHzVhFKsX49j5jlHNWqOk4//DVdGkz+ifT3lujQg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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