SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'dff6b916f23a7bf48183f9b74556563169f2942e8e1c10bff1790e8aa85004f1' 
  AND token = 'xyDFJKzMr7AXLfekQszChGghj//Pa+TN4cv750jg/GE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00015

JSON explain

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