SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4a3de78c9965e2f3ee2758566a4bfb3be7fd1decef46e77c364389e5d91affac' 
  AND token = 'Zc2KAE8nymgH81AF4JwiNDJXmk3zO4famJ/6Q/SefkQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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