SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f894e65b9c37a2e65b3d89b8cfdb912af1673c65da0af24804176bbc2de642a4' 
  AND token = '7fuZC0mXhvDmO8EUNoCwldwAnnm40PhHWnx/kQOyLZU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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