SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6c66b40aefdf892aa8937f2ce445b0c4215ef001f942fb1f628e35842d4f03ed' 
  AND token = '4+lGoiopxtGgsLnqO6xy1FoHqfTNeWAnymKp5rwY2fs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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