SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '275f62638aca95962e26e6bedec4d503ce8aee6604e5f39542afbfd83002efea' 
  AND token = 'l9q5s7H/IvkpZJxwdqhokNNPb0lJ1v40eFlReoVrQ3c=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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