SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '327ba7a05d6c993636ece4dcf35c983883a23583fd2e6224df90fb2282287176' 
  AND token = 'X9TgjIZXgJM1dOutyph42RnzgHG3C1LgRGvqY2leFmQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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