SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'cb7b8f833ccb83b85944b48e26d733543643ec7c36420ffa958abdb734bbd6f0' 
  AND token = 'x7X4uCzI5mrwwkv3Lzjpr5HgKjZv1QMe+jgWUKFtG2U=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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