SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '29fd13ba47531729fdfa2ae56a66c4adbd298a3a1a504d17867f354af6bf935c' 
  AND token = '8MpN477fZFgflk6l9qPhPK/HwXVNedBt7yjzoSAnUh8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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