SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c03e8c8d80436d97acf6f0946d104efbe6119f61b2badc221274e11688a3e80b' 
  AND token = 'wzmxnsihCFEO4WzJxODWedYRdJVj5tAkn7TL8ispEvg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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