SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '0b8c3f38ea468b37fbfa4077b70c321efcc55f5afaf2b06e453bacba197e6c0b' 
  AND token = '9sORzeT6bPMHhzT35Dz/lctQQ3EbBrMK0MDddkEcYdE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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