SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '98f4351939a02d4d99fdb1272d53cfcc30380daceb8ff4419cebdb7a6c4f2403' 
  AND token = 'AGH9wLYHYScf6I+6OcnsIR/ly4Efhq1bd8cXXZHqgkY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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