SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '66c413c67fdb038de3a2f7f43e31047f2e7cc145853c9d437198c902ac6ead84' 
  AND token = 'jOwhJgZuVzwJMyUtD/Yvnf5Fi3UoNdEtdvFgcL+9ZJU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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