SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2668d61bbe6230760bed746e81fd40253e3a9621286115cce7f50ba1e647d42d' 
  AND token = 'gi315i1EAx5cXev//W4lmqihUJxLm3ClmqGJGU2QB+c=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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