SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '37a61ad68f32b4f313316b6971408cf905ba1c6357e34ba6a3ad238fe4d73107' 
  AND token = 'uMLOK3XiSf/3p2qs2uLAMpS++C6oiOltnt9NtYbxw5U=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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