SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3d3a03694eac8fa6881f4630676379100b8b649a1d10c570c2376a49b12251a8' 
  AND token = 'rmozcsq9YUh1SKzQAGIqoKDskgSNeLc7jWmk9H202Hs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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