SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b7555a2dd20593ddf7b1451c1b511df2789b62d7070ae34c1c16839c37d68285' 
  AND token = '3CpUMNF+T3VfY5HDmmenRRYBMXVaJzESjwPYafbViVw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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