SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '81adea2e0ec055080cc80d4da3f9c4f5d794741296edb5163a278331e981ab61' 
  AND token = 'Oiv37Bz33rbvAwqgLUZQ1wgr2c9chjqwwIBS8J6ZVco=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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