SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a56dafb15f4056c6d72dddf8a01fbd3add10494bd1253804b2a7453e6324a699' 
  AND token = 'kfIx/eSi3sh29Dz5fzXj3R/LIxTdK43Pnj1QIEXsxUQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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