SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6c2949b277b0f61037b75f337c4752188ac598a8a871218a07119433064e8480' 
  AND token = 'cb+Ry2vk7HgoJ8z3QNozkqxUmN4pxdXqTooyAkLWrEI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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