SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f234490758fdebaf8e6b47d12cfb0a5b09ec781f1f76fcaf76d9d86745796a5c' 
  AND token = 'AGpr5SDCwt9NjpV1tW31X2MGhuFDY0M9J9s6WvUh/jM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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