SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '13d6fff96567fcace7120e2ea5bda2388bb03352bf8f5a2404c3760dd1dce6e3' 
  AND token = 'HvkiE7ukyl2VagQgEwGBj1rJ1woR3KNn+o/0pODLZMQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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