SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b1215f8c63563f9afda110f613c33a979372c8fc81e4b0269cd14e2e008c6cf2' 
  AND token = 'vsVBmS4p5XgolxFKnotJbph2gZyx/uDUbnQKnoKiZoo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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