SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6c8f44654425005a260377c258aacae39e1773bf633d65cd16c81d5a2518c09f' 
  AND token = 'V9yxfTi0hwVMiWBWqJ/f/JzbLeV0/kZt/RwogxvUHTs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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